Spectroscopic studies on naphthalene in the vapor phase. II. Fluorescence quantum yields from single vibronic levels in the first excited singlet state—behavior of higher excited singlet states

1975 ◽  
Vol 63 (10) ◽  
pp. 4529-4540 ◽  
Author(s):  
M. Stockburger ◽  
H. Gattermann ◽  
W. Klusmann
Keyword(s):  
Phase Ii ◽  
Vapor Phase ◽  
Singlet State ◽  
Spectroscopic Studies ◽  
Quantum Yields ◽  
Excited Singlet ◽  
State Behavior ◽  
Fluorescence Quantum Yields ◽  
Singlet States ◽  
Excited Singlet States

Fluoreszenz -Untersuchungen an Distyrylbenzolen

1988 ◽  
Vol 43 (6) ◽  
pp. 583-590 ◽  
Author(s):  
Dieter Oelkrug ◽  
Klaus Rempfer ◽  
Ellen Prass ◽  
Herbert Meier
Keyword(s):  
Singlet State ◽  
Fluorescence Decay ◽  
Excited Singlet State ◽  
Quantum Yields ◽  
Excited Singlet ◽  
Fluorescence Quantum Yields ◽  
Forbidden Transition ◽  
Decay Times ◽  
Fluorescence Decay Times

Abstract The absorption and fluorescence of three isomeric distyrylbenzenes are investigated as function of temperature. From the fluorescence decay times and fluorescence quantum yields two classes of oligostyrylarenes can be distinguished. A decisive criterion for this classification is, whether the first excited singlet state S1 belongs to an allowed or forbidden transition S0→S1.

Photochemical Reactions of Primary Aromatic Amines with Chloromethanes in Solution. I. Spectrochemical Studies

1989 ◽  
Vol 44 (12) ◽  
pp. 1585-1588 ◽  
Author(s):  
Wojciech Boszczyk ◽  
Tadeusz Latowski
Keyword(s):  
Hydrogen Chloride ◽  
Stability Constants ◽  
Aromatic Amines ◽  
Photochemical Reactions ◽  
Quantum Yields ◽  
Excited Singlet ◽  
Singlet States ◽  
Primary Aromatic Amines ◽  
Excited Singlet States ◽  
Induced Reaction

Interactions were studied of aniline, 4-methoxyaniline and 4-ethoxyaniline with tetrachloromethane, chloroform and dichloromethane in their ground and first excited singlet states. Stability constants of the complexes of these amines with the chloromethanes in cyclohexane were determined as well as their quantum yields of fluorescence in this solvent. The quenching of fluorescence of aniline and its derivatives by the chloromethanes was ascertained and characterized. Quantum yields of the formation of hydrogen chloride, ψΗCl, were measured during photochemically induced reaction of the amines in tetrachloromethane, chloroform and dichloromethane.

The role of the molecular environment for the primary photoprocesses of phenol in solution

1980 ◽  
Vol 58 (19) ◽  
pp. 2006-2010 ◽  
Author(s):  
J. Zechner ◽  
G. Köhler ◽  
G. Grabner ◽  
N. Getoff
Keyword(s):  
Excitation Energy ◽  
Quantum Yields ◽  
Strongly Correlated ◽  
Solvated Electron ◽  
Excited Singlet ◽  
Solvent Interactions ◽  
Singlet States ◽  
Excited Singlet States

Quantum yields of fluorescence as well as of solvated electron and H atom formation have been measured for phenol in several pure solvents and mixtures of varying polarity. The influence of excitation energy has been studied by excitation of phenol in the first and second excited singlet states. The solvent dependences of fluorescence and photoejection parameters are strongly correlated. The results are interpreted in terms of specific solute–solvent interactions, in particular H-bonded structures.

Der Substituenteneinfluß auf die Fluoreszenz des 1.3-Diphenyl-2-pyrazolins / Substituent Effects on the Fluorescence of 1,3-Diphenyl-2-pyrazoline

1976 ◽  
Vol 31 (9) ◽  
pp. 1248-1255 ◽  
Author(s):  
H. Strähle ◽  
W. Seitz ◽  
H. Güsten
Keyword(s):  
Absorption Spectra ◽  
Ground State ◽  
Phenyl Ring ◽  
Fluorescence Spectra ◽  
Singlet State ◽  
Fluorescence Decay ◽  
Quantum Yields ◽  
Excited Singlet ◽  
Fluorescence Quantum Yields ◽  
Absolute Fluorescence

The electronic absorption spectra, absolute fluorescence spectra and fluorescence quantum yields as well as the fluorescence decay times of nine 1,3-diphenyl-2-pyrazolines substituted in the para-position of the 1-phenyl ring and of 19 substituted in the paraposition of the 3-phenyl ring were measured in degassed benzene at room temperature. The fluorescence quantum yields are about 0.90 with the exception of the NO2- and J-substituted 1,3-diphenyl-2-pyrazolines. The fluorescence decay time ranges from 2 to 4 nsec. The natural fluorescence lifetimes determined experimentally agree well with those calculated from the absorption spectra according to STRICKLER and BERG. A plot of the Hammett σp-values versus the energies of the absolute fluorescence maxima of the psubstituted 1- and 3-phenyl ring of the 2-pyrazoline system shows a statistically significant linear correlation with moderate precision. The linearity between ground state substituent constants and fluorescence energies reveals that the relative importance of the inductive and the resonance effects of the substituents remains constant during the transition from the ground state to the relaxed excited singlet state. In the excited singlet state of 1,3-diphenyl-2-pyrazoline the p-substituents provide more room for a larger charge displacement in the intramolecular charge-transfer. The structural bands in the fluorescence spectra resulting from strong electron accepting substituents in the para-position of the 1-phenyl ring are considered as the result of the ring breathing vibration due to a local excitation of the 1-phenyl ring.

The photochemistry of ring-substituted cinnamyl acetates

2006 ◽  
Vol 84 (9) ◽  
pp. 1146-1154 ◽  
Author(s):  
S A Fleming ◽  
L Renault ◽  
E C Grundy ◽  
J A Pincock
Keyword(s):  
Triplet State ◽  
Singlet State ◽  
Acetoxy Group ◽  
Excited Singlet State ◽  
Excited Triplet State ◽  
Quantum Yields ◽  
Excited Singlet ◽  
Major Pathway ◽  
Excited Triplet ◽  
Fluorescence Quantum Yields

The photochemistry of the (E)-cinnamyl acetates ((E)-1-aryl-3-propenyl acetates, 8a–8e) with substituents H, 4-CH3O, 3-CH3O, 4-CF3, and 3-CF3, respectively, was examined in both cyclohexane and methanol solvents. Alkene isomerization (E to Z) occurred more efficiently than other reactions and evidence is presented that this process occurs from the excited triplet state. In a slower process, 1,3-migration of the acetoxy group led to the rearranged 3-aryl-3-propenyl acetate isomers (9a–9e) as the major pathway, particularly in cylohexane. In methanol, the isomeric ethers 3-aryl-3-methoxypropene (14) and 1-aryl-3-methoxypropene (15) were formed by reaction of methanol with the photochemically generated cation. The combined yield of 14 and 15 (95% and 5%, respectively) was quantitative for the 4-methoxyphenyl compound (8b). Independent irradiations of the isomers 9a–9c demonstrated that the ethers 14 and 15 were primary photoproducts from 8 and not secondary photoproducts from 9. Fluorescence quantum yields and excited singlet state lifetimes indicated that the reactions, other than the E to Z isomerization, are from the excited singlet state.Key words: cinnamyl acetates, photochemistry, E/Z isomerization, photocleavage, fluorescence.

Quasiparticle Excitations in Polyenes and Polyacetylene

1987 ◽  
Vol 109 ◽  
Author(s):  
Paul Tavan ◽  
Klaus Schulten
Keyword(s):  
Dispersion Relations ◽  
Excited Singlet ◽  
Quasi Particle ◽  
Double Excitation ◽  
Singlet States ◽  
Excited Singlet States ◽  
Electron Excitations ◽  
Quasiparticle Excitations

ABSTRACTWe apply the Pariser-Parr-Pople Hamiltonian to study many-electron excitations in polyenes and polyacetylene. The excited singlet states of polyenes, calculated by a multireference double excitation expansion, are classified as quasi-particle excitations, namely as triplet-triplet magnons and particle-hole excitons. From finite polyene spectra we derive approximate dispersion relations for these quasi-particles in the infinite polyene, i.e. polyacetylene.

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